Electrically operable strikes are well known in the art and, for example, they are used frequently in connection with the main access door of an apartment building to prevent entry into the building until a solenoid associated with the strike is electrically energized to permit pivoting of the strike keeper. See, for example, U.S. Pat. Nos. 6,634,685; 5,127,691; 4,984,835; 4,471,983; 3,638,984 and 3,749,435. It is also known in the art to prevent release of the latch or keeper of the strike and opening of the door by electrically energizing the solenoid. Normally, the solenoid is energized by means of a circuit completing switch remote from the strike.
In addition, the known strikes usually require several components, such as pivotable levers, etc. which increases the assembly problems and the likelihood of malfunctioning because of misalignment, binding or corrosion.
In general, prior art strikes comprise a single solenoid which has a winding of a conductor which, when electrically energized, actuates an armature which has a locking member connected thereto and biased by a spring so that the locking member prevents pivoting of the keeper unless the solenoid is electrically energized. To keep the energizing current low, the biasing spring usually has a force which is only slightly more than the force required to return the locking member and the armature to their locking or unlocking positions. Such spring return force may, at times, such as with misalignment of parts, accumulation of foreign matter, etc., be insufficient to return them to their unlocking or locking positions.
It is also known in the art to use an air actuated piston and cylinder assembly with the piston connected to the locking member to actuate the locking member.